King David was the bomb dot com. They probably called him that before the Internet—that's how much people loved him. So it makes sense that there was an enormous literary and artistic effort to glorify David and his descendants.
Because David's rule is always connected with the might of God, scholars speculate that the writers of Psalms, and much of the Bible, worked in David's court. Why not make your boss sound awesome? Much of Psalms is even attributed directly to David, and the Bible in general works hard to craft an image of a good king who was a writer and a warrior.
Sure, David reigned three thousand years ago, but we know a good Golden Age when we see one.